Steerable or deflectable tip cardiovascular catheters are useful in many applications, offering improved maneuverability when compared to catheters with fixed tip curves. A deflectable catheter having a thru lumen has substantial clinical significance in left heart therapy delivery procedures by allowing a guide wire or contrast agent to be used during advancement of a distal tip of the catheter to a target area of a body, such as the coronary sinus and the associated coronary veins. The thru-lumen enables the use of a guide wire and/or contrast agent, which increases the probability of accurate and efficient placement of the catheter and decreases the chance of venous trauma caused by multiple repositioning of the catheter within the tortuous path.
In addition, one or more pull wires, positioned within lumens extending from a handle to the distal end of the catheter, are commonly included within catheters to enable the catheter to be deflected by manipulating the pull wire through the handle, which in turn compresses a distal end of the catheter, creating the deflection along the distal end. When a thru lumen is also incorporated in a catheter having one or more pull wires, the pull wire is segregated from the thru lumen by using separate lumens for the pull wire and the thru lumen. Due to the added wall thickness of the separate lumens, the addition of the pull wire lumen or lumens separate from the thru lumen reduces the amount of area available for the thru lumen, which, unless the outer diameter of the catheter body is increased, reduces the maximum thru lumen diameter, making introduction of a contrast agent or advancement of a guide wire through the thru lumen problematic.
In order to allow passage of the catheter through existing therapy delivery devices, the outer diameter of the deflectable catheter must be 7 French or less. However, such restriction in possible diametric parameters of the catheter make At the same time, the inventors have found that in order to pass enough contrast agent through the thru lumen to be clinically useful, the thru lumen must have a diameter that is greater than 0.021 inches. In addition, the thru lumen must be large enough to allow passage of an introducer type guide wire, which can range in size up to 0.035 inches with 0.025 and 0.035 inches being the most common sized guide wire. All of these dimensional requirements, including the need for a thru lumen for manipulating a pull wire, being sized so as to be able to be advanced through existing therapy delivery devices, being able to pass useful amounts of contrast, and being able to allow passage of an introducer type guide wire, make designing a single catheter with all of these features difficult.